strftime formatting of milliseconds

[jurta]

Steps to reproduce

• Timex.now |> Timex.format!("%Y/%m/%d %T.%L", :strftime)
• or just Timex.now |> Timex.format!("%L", :strftime)
• fails with:

** (Timex.Format.FormatError) got {:formatter, :unsupported_token, :ms} while retrieving Exception.message/1 for %Timex.Format.FormatError{message: {:formatter, :unsupported_token, :ms}} (expected a string)
    (timex) lib/format/datetime/formatter.ex:58: Timex.Format.DateTime.Formatter.lformat!/4

Description of issue

• Expected to return a string with milliseconds (000..999) as described in the documentation.

Thanks!

[prook]

The FormatError reason handling may be improved, but the original problem remains: "%L" blows up with {:formatter, :unsupported_token, :ms}, because Timex.Format.DateTime.Formatter lacks format_token for :ms type.